Subscription television system

• US 4,533,949 A
• Filed: 09/08/1982
• Issued: 08/06/1985
• Est. Priority Date: 09/10/1981
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Okada, Takashi, Fujimura, Yasushi, Yamagiwa, Kazuo
• Primary Examiner(s): BUCZINSKI, STEPHEN C
• Application Number:
  US06/415,836
• Time in Patent Office: 1,063 Days
• Field of Search: 358/114, 358/117, 358/118, 358/122, 358/123, 358/119, 358/121, 360/27
• US Class Current: 380/201
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00282 the key being stored in the content area, e.g. program area, data area or user area key stored in a management area G11B20/00297
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/167 Systems rendering the television signal unintelligible and subsequently intelligible
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

In a subscription television system, only a video signal for a specific program is scrambled in a television signal in accordance with a predetermined scrambling mode. A key signal, used for unscrambling the scrambled video signal, is generated in response to the scrambling mode. The key signal is transmitted after the scrambled program.

Claims

1. A subscription television system requiring time-shifted viewing comprising,

means for scrambling at least one of a video signal and an audio signal for a specific television program in accordance with a predetermined scrambling mode to produce a scrambled program signal,

means for generating a control signal in response to said predetermined scrambling mode, said control signal including a key signal for unscrambling said scrambled program signal,

means for combining said control signal with said scrambled program signal such that said key signal is appended to one of said video and audio signals at the end of said scrambled program signal;

and

means for transmitting said scrambled program signal and said key signal such that said key signal is transmitted after all of said scrambled program signal has been transmitted.

2. A system according to claim 1, in which said means for scrambling includes means for changing said scrambling mode for different television programs.

3. A system according to claim 2, in which said control signal further includes a program code signal for identifying said key signal for said specific television program.

4. The system of claim 1;

wherein said means for scrambling includes means for reducing the signal level of said video signal at predetermined intervals.

5. The system of claim 1;

wherein said video signal has a burst signal; and

wherein said means for scrambling includes means for changing the phase of said burst signal at predetermined intervals.

6. The system of claim 1;

wherein said video signal has horizontal intervals; and

wherein said means for scrambling includes means for replacing at least one portion of one horizontal interval of said video signal with another portion of said horizontal interval of said video signal.

7. The system of claim 1;

wherein said means for scrambling includes means for supplying said video signal and a pseudo-ghost signal corresponding thereto as the video portion of said scrambled program signal.

8. The system of claim 1;

wherein said means for scrambling includes means for supplying said video signal with left and right reversed as the video portion of said scrambled program signal.

9. The system of claim 1;

wherein said means for scrambling includes means for replacing at least one portion of said audio signal with another portion of said audio signal.

10. The system of claim 1;

wherein said means for scrambling includes means for supplying said audio signal and a part of said audio signal in reverse as the audio portion of said scrambled television signal.

13. Apparatus according to claim 5, in which said unscrambling means includes means for indentifying a program code signal, said program code being supplied to said memory means to read out said key signal of said specific program therefrom.

11. For use in a time-shift subscription television system, an apparatus for unscrambling television signals transmitted as a scrambled program signal followed by a key signal, said apparatus comprising:

means for recording said scrambled program signal on a recording medium prior to receiving said key signal;

memory means for storing said key signal following recording of said scrambled program and for selectively outputting same;

means for reproducing said scrambled program signal from said recording medium; and

unscrambler means connected to receive said reproduced scrambled program signal and said key signal output from said memory means for unscrambling said scrambled program signal in accordance with said key signal from said memory means.

12. Apparatus according to claim 11, in which said scrambled program signal comprises a television signal with only a video portion thereof having been scrambled, said video signal being supplied to said recording means to be synchronized with a synchronizing signal included in said video signal which is not scrambled.

14. The apparatus of claim 11;

wherein said recording medium is video tape, and said means for recording and for reproducing includes a video tape recorder.

15. A system for use in time-shifting scrambled video and audio television signals comprising:

scrambler means for scrambling at least one of said video and audio signals of the television signal to produce a scrambled program signal according to a predetermined scrambling mode;

means for generating a control signal characteristic of said predetermined scrambling mode for use in unscrambling said scrambled television signal;

means for appending said control signal to the end of said scrambled program signal

transmitter means for transmitting said scrambled program signal and said control signal in the sequence with said control signal appended to said scrambled program signal;

recorder means for recording on a record medium said scrambled program signal transmitted by said transmitter means;

memory means for storing said control signal transmitted by said transmitter means after said program signal is recorded by said recorder means;

reproducing means for reproducing said scrambled program signal recorded on said record medium; and

descrambler means receiving said reproduced program signal and said control signal stored in said memory means for descrambling program signal in accordance with said control signal from said memory means.

16. The system of claim 15;

wherein said record medium is video tape; and

wherein said recorder means and said reproducing means include a video tape recorder.

17. The system of claim 15;

wherein said scrambler means includes means for scrambling both said video signal and said audio signal.

18. The system of claim 15;

wherein said scrambler means includes means for changing said scrambling mode.

19. A method for use in a television subscription system comprising the steps of:

scrambling at least one of the video and audio signals of a television signal to produce a scrambled program signal in accordance with a selected scrambling mode;

generating a control signal characteristic of said selected scrambling mode for use in descrambling said scrambled program signal;

appending said control signal to the end of said scrambled program signal;

transmitting first said scrambled program signal followed by said appended control signal;

recording on a record medium said transmitted scrambled program signal;

storing in a memory said transmitted control signal after said program signal is recorded on said record medium;

reproducing said scrambled program signal from said record medium;

reading out said control signal from said memory; and

descrambling said scrambled program signal in accordance with said control signal read out from said memory.